Slightly off-topic, but how is the 11...Nd7 line doing nowadays? I have good memories playing this line when I was younger, before switching to the Marshall. I remember it being considered nearly refuted a few times. Is Black meant to be okay?

I download games from The Week In Chess. From 2012 to 2016, white scores only 51% after 11...Nd7. I think theory is also positive on the Keres line. If you are just catching up, like me, the surprise is that after 12Nbd2 black prefers exd to the earlier cxd. The idea is to go into a Benoni type structure after 12Nbd2 exd 13 cxd Nc6 14d5 Nce5. At a glance it may not look like much. However black has some interesting resources on the king side. After 15Nxe5 Nxe5 16f4 Ng6 17Nf3, black can consider 17...Bh4 or 17...f5.

I prefer the Open to the Closed Ruy Lopez, but dabble in the Closed from time to time. I think black should always consider d5 by white. I suppose it could be labelled the "ultra-closed" variation. How does black best arrange his pieces after white separates black's king side from his queen side?

ChessPublishing has provided a variety of opinions on 12 d5. These are from various annotated games, and, possibly commentators:

"I continue to think that this move is excellent and leaves the Keres Variation under a cloud."

"This looks premature as Black is well placed to launch a counterattack with ... f7-f5."

"Although this is good in many lines of the Closed Spanish, in this position it gives Black excellent counterplay."

"For a long time it has been established that Black should not fear this position. Keres himself thought that this move was premature. In fact, the present game seems to show the opposite, and puts the whole Keres variation in doubt."

For me at least, the next step would be to put eyes on the board and play through some games.

Slightly off-topic, but how is the 11...Nd7 line doing nowadays? I have good memories playing this line when I was younger, before switching to the Marshall. I remember it being considered nearly refuted a few times. Is Black meant to be okay?

Correspondence should normally nowadays be very drawish. However just look at the number of wins for white in the last year. The previous years look similar. That is really abnormal. I wasn't exaggerating with my catastrophic statement.A recent modelgame of how white crushes black. This game can't be found in the Chessbase online database yet.

Don't get distracted by whites rating. I checked his profile on iccf see https://www.iccf.com/player?id=690538 and I found out that he has not lost any game yet in a span of 42 games. The rating of the Cuban player is raising very fast.

I think annotated GM games are the way to go. If you study Keres, Fischer, and Karpov in roughly that order, you can't go too far wrong.

Can anyone recommend a particular good source for Keres' games as black in the Spanish? Doesn't have to be the Chigorin. Keres is one player both my library and general education don't have too much about.

I dislike 12.d5 from blacks point of view. White scores there very well.

True however you need to make a clear distinction between correspondence and otb. The most recent scores in correspondence were catastrophic while in otb black still has decent results.In 2012 I wrote an article on my blog about the weak 12...c4 see http://schaken-brabo.blogspot.be/2012/09/de-spaanse-doorschuifvariant.htmlIn 2015 I touched upon the mainline with 12...Bd7. I played a very nice draw with black against a former Russian champion. Anyway I clearly note there are problems for black see http://chess-brabo.blogspot.com/2015/10/to-disarm.htmlVery recently I started to look at 12...Nd7. There is almost 0 theory of it and is very closely related to the 11...Nd7 12.d5 systems.

I'd already decided that 12.d5 is something to take a very close look at before even proceeding with anything else, without reaching too many solid conclusions. 12.d5 Bd7 13.b3 and then 13...Rfb8!? looked interesting or even 13...Rfe8 (to defend the bishop, which is useful vs Ba3 ideas).

In any case I noticed that Mark Hebden has several times recently played the line 12.Nbd2 Be6!? 13.d5 Bd7 14.b3 as black which reaches the 12.d5 variation a whole tempo down.

He seems to like continuing 14...g6 15.Nf1 Nh5 since with this move over 16.Bh6 Ng7 is not so big a deal. And with white playing 15.Nf1 to release the Bc1 then c3-c4 ideas are less likely to be good.

Real life has kept me too busy from looking into this deeper but I don't see 12.d5 as a reason to avoid 11...Qc7 at the moment.

(p.s. I'm interested in correspondence games for the theoretical points but am exclusively an OTB player)

I dislike 12.d5 from blacks point of view. White scores there very well.

True however you need to make a clear distinction between correspondence and otb. The most recent scores in correspondence were catastrophic while in otb black still has decent results.In 2012 I wrote an article on my blog about the weak 12...c4 see http://schaken-brabo.blogspot.be/2012/09/de-spaanse-doorschuifvariant.htmlIn 2015 I touched upon the mainline with 12...Bd7. I played a very nice draw with black against a former Russian champion. Anyway I clearly note there are problems for black see http://chess-brabo.blogspot.com/2015/10/to-disarm.htmlVery recently I started to look at 12...Nd7. There is almost 0 theory of it and is very closely related to the 11...Nd7 12.d5 systems.